Study On Ecological Risk Assessment Of Land Consolidation

Land is human basis of produce and maintenance materials. Along with the explosive growth of economy and society and the accelerating of urbanization process, cultivated land-the important means of production is getting unceasing nibble, and the situation of cultivated land protection becomes increasingly grim nowadays. In order to carry out the aim of the total cultivated land dynamic equilibrium and ensure grain safety, land consolidation is becoming important grand strategy. However, with the aid of a series of biological measure and engineering measures, field, water, road, forest and village are comprehensively renovated, land consolidation brings many direct or indirect harmful influence (ecological risk) inevitably for ecological course and the environmental essential factors such as hydrology, soil, vegetation, atmosphere and biology of project district and its background area .The purpose of introducing ecological risk assessment regime into land consolidation is to find out the possible, disadvantageous ecological effect, and assess the scope and size of its harm. The research has important theoretical meaning and realistic meaning for avoiding ecological risk and founding the ecological environmentally friendly land consolidation pattern.On the basis of summarizing existing resources of ecological assessment of land consolidation and ecological risk assessment, and facing the appeal of ecology management, the paper introduces theoretic and methods of ecological risk assessment into the domain environmental impact assessment of land consolidation. The principium, program and methods of ecological risk assessment of land consolidation are carried out, and complete, systematic theoretic and methods system of ecological risk assessment of land consolidation is formed. This paper has carried out the research of following few aspects mainly.(1)Applying landscape ecology principle, this paper analyses the relation between land consolidation and ecological environment. Landscape principle of dynamic and process disturbance of land consolidation is studied; driving factor -landscape change-ecological influence model followed by landscape change that aroused by land consolidation is carried out; approach and effect of landscape ecological impact in land consolidation area is analyzed. The analysis of the relation between land consolidation and ecological environment is the basis of building conceptual model of contiguity and exposure relation between risk source risk and risk receptor, and has positive meaning for ecological risk assessment of land consolidation and ecology protect.(2) This paper founds theoretical frame of ecological risk assessment of land consolidation and has discussed risk assessment process in detail. Ecological risk assessment of land consolidation includes eight steps: problem plans and forms, receptor analysis and ecological endpoint choosing, risk source analysis, conceptual model and analysis plan, exposure-hazard analysis, risk characterization, uncertainty analysis, risk management. In which land consolidation ecological risk source can be summed up: land leveling, damage of vegetation, channel and road construction and scramble parcel merging, crops implant and incorporation with extra soil, residential area constructing and dilatation along with massive land development. Conceptual Model reveals and describes the relation of exposure and respondence between risk resource and receptor. Risk characterization is the course of evaluating the size of harm role as well as the probability that occurs, it is the key part of risk appraisement, and now there are two analysis models mainly: comprehensive index model and relative risk model (RRM).Exposure-hazard analysis can mostly aim at the 4 aspects: micro topography, soil properties, water environment and Organisms, habitat, landscape. The quantitative analysis method -Monte Carlo Simulation that applied extensively currently is adopted for uncertainty analysis, and the tentative research including uncertainty source and assessment technique in the course of ecological risk assessment of land consolidation is expanded. As a necessary step of ecological risk assessment, according to the result of risk characterization, risk management puts forward reasonable risk management measure in order to minimize the ecological risk of land consolidation.(3) This paper has discussed the comprehensive index assessment model that applies to land consolidation project or land consolidation area that has major information. According to the influence for natural system, ecosystem function and landscape of land consolidation, index system of ecological risk assessment of land consolidation is carried out. This paper has also put forward the many methods for risk characterization such as analytic hierarchy process, the fuzzy comprehensive evaluation, the gray evaluation model, sensitive factor model, qualitative analysis and consequence. And the general application flow that is "contributing factor- machine made analysis→risk sub-district partition→sensitive factor analysis and qualitative analysis and consequence→mathematical model analysis→comprehensive valuation" is developed. Then, applying comprehensive index model, empirical research of coastal mudflat development project ecological risk assessment in Dafeng County is done. Grass beach area, reed ground ,mudflat, tunnel and pool, river and channel, resident point are regarded as risk receptor at coastal mudflat development project ecological risk assessment in Dafeng County. Following the above mentioned flow and model, risk grades of different assessment sub-districts is determined. This assessment result has passed the uncertainty inspection of Monte Carlo Simulation, so that it is successful to apply comprehensive index assessment model in land consolidation project ecological risk assessment. Appraisal results of coastal mudflat development project ecological risk assessment in Dafeng County shows: coastal mudflat development project district can divide into 5 risk grades: High sub-district (Ⅰlevel), area takes 21.20% of project district; Higher sub-district (Ⅱlevel) take 5.58%; Medium sub-district (Ⅲlevel) take 70.07%; Low sub-district (Ⅳlevel) to take 1.62%; Weak sub-district (Ⅴlevel) take 1.53%.And according to different assessment risk grade, the risk management measures such as habitat adjustment is put forward.(4)The relative risk model (RRM) that was developed abroad recently is introduced into ecological risk assessment of land consolidation. In order to reduce the uncertainty in regional risk assessment, the definite method of relative dense degree between different area risk pressure source and habitat is ameliorated, and intrinsic fragment assignment law is substituted using ratio method, so original discrete intensity rank is converted to consecutive point value, and the comparison of risk level between different sub-districts is actualized. The assessment result of RRM model indicates the relative risk relation between different assessment sub-districts; therefore apply to the region ecological risk assessment with relatively less information. Applying RRM, ecological risk assessment of land consolidation in Dafeng County is done. Species diversity, habitat quality, landscape pattern are regarded as ecological endpoint. Though conceptual model of exposure and respond route between risk source, pressure, habitat change, ecological endpoint, the paper introduces two indexes: pressure density, habitat abundance loss into reckoning the degree of exposure and respond between pressure and ecological endpoint. Finally through comprehensive product of pressure density, habitat abundance loss, exposure coefficient, respond coefficient, the latent risk value according to different risk source type, different habitat change, different ecological endpoint and different risk sub-districts is reckoned. Empirical research shows: East in Dafeng County is land developing zone mostly, though, effective cultivated land is more, but ecological risk is higher; Central section belongs to medium risk sub-district and low risk sub-district mostly; West is cultivated land consolidation zone and abandoned land zone, and belongs to weak risk district, so West should become first selection area for land consolidation. Though relatively risk model shows a kind of relatively risk relation between risk sub-districts, it also can realize the grade assessment between each kind of risk source and habitat of different risk sub-districts. The result of region ecological risk assessment of land consolidation has not only passed the uncertainty inspection of Monte Carlo Simulation also coincides with the conclusion from field survey.(5)This paper, not only, according to deferent level appraisement sub-district, has put forward the countermeasure that reduces ecological risk, but also has made the policy suggestion of avoiding ecological risk. The suggestion includes:①developing appropriate unused land, increasing cultivated land consolidation and abandoned land consolidation;②habitat adjustment is necessary because of developing important ecological resource such as wetland;③applying the landscape ecological program and design of land consolidation project, carrying out landscape ecological type land consolidation;④establishing land consolidation appraisement system of ecological environment, developing environmental-friendly agriculture appropriately.The paper is divided into five parts. The first part, including chapter 1, focuses on the objective, content, research framework, technical route and the analysis method etc. the second part, including chapter 2-3, focuses on the advances in researching ecological risk assessment and ecological problem of land consolidation and the basic theories for ecological risk assessment of land consolidation. The third part, including chapter 4-6, focuses on, the relation analyses between land consolidation and ecological environment, as well as the concept, program, model and method of ecological risk assessment of land consolidation. The fourth part, including chapter 7-8, focuses on the empirical study. Based on comprehensive index model and relative risk model (RRM) differently, empirical research of coastal mudflat development project ecological risk assessment in Dafeng County and ecological risk assessment of land consolidation in Dafeng County are done. The fifth part, including chapter 9, focuses on the main conclusion and relative countermeasures and suggestions for avoiding ecological risk.